In general, the invention relates to hard floor panels, which, at two or more sides, are provided with coupling parts and which can be provided on an existing subfloor, either floatingly or glued, or in any other manner, in order to form a floor covering. Hereby, the invention is intended in particular for laminate panels, for example, with a printed decor and a top structure on the basis of synthetic material, prefabricated parquet, with panels mostly consisting of several layers of material with, at the upper side, a top layer of solid wood with a thickness of several millimeters, veneer parquet consisting of panels having a layer of veneer at their upper side, or solid parquet. This does not exclude that the invention is also applied for other hard floor panels, whether or not composed of several parts, for example, with top layers of other materials, such as, amongst others, cork, stone or stone-like materials, linoleum, carpet, and so on.
According to a first aspect, the invention relates to a method for manufacturing floor panels, which, as aforementioned, are provided with coupling parts at least at two opposite sides.
It is known that such coupling parts can be formed by means of a classical tongue and groove connection, wherein these, when installing the floor panels, possibly are glued into each other, or by means of mechanical coupling parts providing for a mutual locking of the floor panels in horizontal as well as in vertical directions, for example, as described in the international patent application WO 97/47834. This document describes how the respective coupling parts at two opposite sides can be formed in a continuous machine, in other words, while moving the floor panel over rotating mechanical cutting tools. This method is also called “continuous milling”.
It is also known, for example, from the patent document WO 2004/037502, when using a continuous machine, to provide a guiding groove approximately in the middle of the lower side of flat panels by means of a saw treatment and to move the panels with this guiding groove over a guiding portion, while providing two opposite sides of the panels with profiled edge regions that comprise coupling parts. Applying this technique guarantees the parallelism of the two respective opposite sides, however, the presence of the guiding groove in the center of the panels may lead to undesired effects, such as, for example, the local weakening of the panels, the heightened risk of moisture penetration and/or warping and the like. The described continuous machine relates to a machine in which the panels are transported by means of an air bed and belts. Hereby, the air bed presses the panels upward against two belts, which, by means of friction, carry the panels along and convey them through the machine.
With such transport, considerably higher passage speeds can be achieved than with traditional chain conveyance systems.